Since 1830 when the traditional ring spinning machine was invented, more than 180 years has passed and the ring spinning machine has become the world's most widely used spinning main equipment. Spinning production capacity of China's textile industry has currently been more than 50% of the global total, and there are 120 million cotton spindles and about 4 million wool spindles.
Traditional ring spinning machine has a unique twist mechanism and the special structure of yarn spinning, resulting in soft and fluffy yarn, cannot be replaced by any new spinning technology.
However, with the development of the modern textile industry, people pay more attention to the inherent defects of the ring spinning machine. The prolonged production practice shows that the key technical bottlenecks of the ring spinning machine are the spinning end breakage and unevenness, and that the strength of the yarn in the twisting triangle area is less than the spinning tension, leading to the spinning end breakage and unevenness. Therefore, reducing the spinning tension while increasing the strength of the yarn is the preferred target task of the spinning field researchers.
Spinning tension is the force that is transmitted to the twisting triangle area by the sliver of the bottom of the ring spinning machine. The spinning tension is a composite force, and may change every moment.
Spinning tension is the algebraic sum of five variable forces: winding tension, the damping force of the bead ring, the centrifugal force of the air ring, ring board move additional dynamic tension and the yarn guide damping tension. The adverse consequences of excessive spinning tension acting on the twisting point are that the fibers in the yarn will slip and produce unexpected draft, making the yarn uneven and increasing snicks. Even the spinning end may break.
The spinning strength refers to the spinning strength in the twist triangle area. There are large differences in yarn strength. The strength of yarn depends on the fiber tensile strength, fiber length, curl roughness surface and the applied twist level. With the increase of the twist, the holding force of the fibers in the yarn will increase, and the yarn strength will also increase. Twist factor is not only a major factor but also a direct factor. Spinning strength is determined by the following factors: fiber breaking strength, fiber length, roller grip force, and twisting triangle width and height. Direct factor is the height of the twisting triangle, and twisting triangle height determines the roller nip holding the amount of fiber. When twisting triangle height is lower, more fibers can be controlled in the twisting triangle. Increasing the twist and torque is the most effective measure to reduce the twisting triangle height. There is a great difference between increasing spinning strength by increasing the twist and increasing yarn strength by increasing the twist. Increasing the yarn twist can increase the holding force of fibers, whereas increasing the twist of the twisting triangle can only reduce the twisting triangle height and increase the fibers held by the roller. According to relevant information, the spinning strength is very low, for example, the spinning strength of 28tex cotton yarn is about 90˜150 cN. However the strength of yarn is about 400 cN. Therefore, increasing the spinning strength can prevent breakage and improve the sliver evenness. Increasing the twist in the twisting triangle is the most effective technical measure to improve the quality of yarn and prevent breakage, but it makes the fabric feel stiffer.
Because of the above defects of the ring spinning machine, application of the ring spinning machine is limited. If the spinning speed cannot be further increased and spindle speed remains about 15000 r/min, the traditional ring spinning machine cannot spun the yarn lower than 330 twists per meter, and that requires greater spinning fiber length and short fiber content.
For the defects regarding high spinning tension and low spinning strength of ring spinning machine, people continue to study and explore ways to improve. The current improvements are as follows:
(1) Using finger-shaped ingot end ingot spinning. The advantage of this technique is the spinning tension significantly being improved and it requires simple structure. The disadvantages are that the spinning strength does not increase but decreases, and the friction between the yarn and bobbin becomes more severe and produces more lint;(2) Using the magnetic rotary yarn guide in place of the yarn guide. This can produce the false twist effect and the spinning twist can be transmitted to the front roller nip, and reduce the twisting triangle area. Spinning strength can be improved by about 20%, and spinning speed can also be improved by about 20%. The low-twist yarn can be spun. The disadvantages are the splicing operation being inconvenient, the high manufacturing cost of the yarn guide, and the low efficiency of false-twist.(3) Chinese patent No. 201010237244.3 discloses a high-strength, low-tension spinning device, equipped with yarn tension damping needle holding the false twist. The advantages of this device are the lower spinning tension, and the improved spinning strength. The disadvantage is that the splicing operation is more inconvenient;(4) Chinese patent No. 201110129873.9 discloses using a pair of the dust cages in the form of friction false twist for compact wet spinning. The advantages are the increased spinning strength, the reduced the spinning tension and a more convenient splicing operation. The disadvantage is that the suction of the dust cages motor needs more power;(5) Chinese patent No. 02118588.3 proposes a method and apparatus to reduce spinning tension in spinning low twist yarn. The disadvantage is that the spinning strength cannot be improved. Using the provided fiber splitting mechanism, the amount of fiber held by roller decreases; the yarn evenness is deteriorated; snicks are increased; the efficiency of false-twist is lower and the splicing operation is inconvenient;(6) U.S. Pat. No. 7,096,655 B2 is comparable with Chinese patent application 02118588.1 Except for having a more convenient operation, it has the same defects and problems.